1. Field of the Invention
The present invention relates generally to non-ratiometric sensors, and more particularly to, a method for cancellation of error between digital electronics and a non-ratiometric sensor.
2. Description of the Related Art
A ratiometric sensor is typically referred to as a sensor that shares the same voltage source and ground that is used by an analog to digital converter that is monitoring it. As a result, any error that might occur in the reading of the sensor by the analog to digital converter due to differences in voltage across both devices is eliminated.
However, a sensor that cannot share the same voltage source as the analog to digital converter is typically called non-ratiometric. As a result, the readings of the sensor by the analog to digital converter are susceptible to differences in the voltage source used by each device.
An example of a non-ratiometric sensor used in automotive applications is a methanol content sensor. The methanol content sensor includes a microprocessor to provide methanol content information of fuel used by an engine in an automotive vehicle. However, one disadvantage is that the methanol content sensor is non-ratiometric to the analog to digital converter of an engine controller monitoring the sensor. That is, since the methanol content sensor is not powered by the engine controller's voltage source, there could be error when the engine controller reads the methanol content sensor's signal voltage due to the tolerances or differences of each device's voltage source. Therefore, there is a need in the art to cancel this error.